Government:
Empire with an Emperor and council of ministers. The current Emperor is J'son of Spartax. The title of Emperor is passed down by heredity. The previous Emperor was E'son who was the father of J'son.

Racial Make Up:
The Spartoi are said to have splintered off from the Shi'ar. However, they appear to be humans. They are different than humans on some level in that they have much longer lives. J'son for example is middle aged and is over a 100 years old. They do not appear to be stronger, or faster than humans.

History:
Not much is known other than they have an affiliation with the Shi'ar Empire and at one point splintered off.

Line of Spartoi Emperors
E'son --> J'son --> Starlord (Has not taken up right to rule)

The planet Spartax recieved some concept art for the movie Guardians of the Galaxy. As Starlord's father is brought up multiple times in the movie it can be suspected it will play a part in the 2nd film. However, James Gunn has said that Starlord's father will not be the same character as in the comics.

Gamora also speculates on what in Quill's blood allowed him to hold the Power gem longer than a normal human. He could be Spartoi or something else. Though the Spartoi do not appear very different than humans they do live much longer lives in the comics.